Diphthamide
Chemical compound
Diphthamide is a post-translationally modified histidine amino acid found in archaeal and eukaryotic elongation factor 2 (eEF-2).
Dipthamide is named after the toxin produced by the bacterium Corynebacterium diphtheriae, which targets diphthamide. Besides this toxin, it is also targeted by exotoxin A from Pseudomonas aeruginosa. It is the only target of these toxins.
01Structure and biosynthesis
Diphthamide is proposed to be a 2-[3-carboxyamido-3-(trimethylammonio)propyl]histidine. Though this structure has been confirmed by X-ray crystallography, its stereochemistry is uncertain.
Diphthamide is biosynthesized from histidine and S-adenosyl methionine (SAM). The side chain bound to imidazole group and all methyl groups come from SAM. The whole synthesis takes place in three steps:
- transfer of 3-amino-3-carboxypropyl group from SAM
- transfer of three methyl groups from SAM, synthesis of diphtine
- amidation, synthesis of diphthamide
In eukaryotes, this biosynthetic pathway contains a total of seven genes (Dph1-7).
02Biological function
Diphthamide ensures translation fidelity.
The presence or absence of diphthamide is known to affect NF-κB or death receptor pathways.
Sources and credits
This article is adapted from the Wikipedia article “Diphthamide”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Diphthamide.png by Edgar181, Public domain
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